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Primary Qs


From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Tuesday, September 23, 1997 2:49 PM
To: 	Tesla List
Subject: 	Re: Primary Qs

John,
     You're observing M on a learning curve here...
 
> From:   FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
> Sent:   Tuesday, September 23, 1997 4:53 AM
> To:     tesla-at-pupman-dot-com
> Subject:    Re: Primary Qs
> 
> In a message dated 97-09-22 22:31:39 EDT, you write:
> 
> <<     There is no doubt my neon was killed by a "kickback". For 
> > months/years I have been wondering how a voltage higher than that 
> > generated by the transformer could appear across the transformer 
> > terminals (resonant charging and wide-set gaps aside). The answer 
> > lies in the impedance of the transformer at the RF frequencies. If 
> > some energy still remains in the sec of the coil after the gap has 
> > gone out, it is coupled back to a series-tuned primary which is now 
> > in series with an ultra high impedance presented by the transformer.
> > My filter setup prevents the transformer ringing with the filter caps
> > but in the process, I have boosted the impedance across the 
> > transformer terminals. I should have used filter caps big enough to 
> > limit the rise of a moderate amount of energy that could be fed back 
> > while at the same time ensuring an unfavourable ring frequency with 
> > the transformer. The only simple answer I have right now is bigger 
> > filter caps. Back to the lab.
>  
> > :(
> > Malcolm
>   >>
> 
> Malcolm, all,
> 
> I have seen horrific kickback in both pulsed spark-gap and pulsed
> tube type coils.  Static gaps which fire intermittently, or quench
> strangely may be causing a similar effect.  Sub-optimal spark-
> loading of the secondary/toroid may also allow the secondary to
> ring longer than desired, and couple more energy into the high
> impedance series neon circuit as you said.  In my TC, I obtain 
> rather fast resonator ring down...less time for the neon tar to 
> carbonize?

Don't know.
 
> If it's kickback that's doing the damage, then maybe resonant
> charging is relatively completely safe.  Have you estimated the
> peak voltages of the kickback in your system?

About 20kV+ judging by the "safety" gap setting. It was as if a small 
amount of energy suddenly ran into a brick wall. I used to think that 
resonant charging was the problem until I saw this. I still think 
overvolting is a problem but letting resonant charging take one up to 
peak o/c transformer voltage would seem to be just fine.

> Would simple 3k ohm resistors in series with the neon output
> leads reduce the RF enough, esp. with some bypass caps to
> ground?

I had my much loved "filter" board in the line when all this happened.
 
> Just tossing out some thoughts here,

Thanks. This one deserves to be cracked. It is a problem for 
everybody. I'll do more work on it when I get another neon.

Malcolm